Study On The Synthesis Of Organic Selenium/Tellurium Ethers

In recent years,with the widespread use of organic sulfides in organic synthesis,selenium/tellurium ethers,which are also organic chalcogenide compounds,have gradually received widespread attention from chemists in the pharmaceutical and agrochemical industries.At present,it has been reported that a more extensive method of synthesizing selenium/tellurium ethers are that with the participation of a transition metal,the organic selenium/telluride precursors are directly coupled with an aryl halide to obtain a selenium/tellurium ethers compound,but this method has a transition metal participation,the reaction cost is high,and a large amount of metal scrap is generated during the reaction.In this thesis,a milder,cheaper,and environmentally friendly method is adopted.In the absence of transition metals,the oxidation of trichloroisocyanuric acid(TCCA)promotes the occurrence of C-Se/C-Te cross coupling reaction to obtain selenium/tellurium ethers product.The specific research process is as follows:The first part:Based on the coupling reaction of diselenyl ether and aryl halide that transition metal participates in,a new method for preparing selenide with equivalent TCCA as oxidant was developed.Using 4-methylphenylboronic acid and diphenyl diselenide as the template reaction,after the optimization of the conditions,the optimal reaction conditions were determined:0.66 equiv.TCCA as the oxidant,THF as the solvent,and the reaction at 25 ~oC for 4 h.The experimental results show that the oxidation reaction system has good functional group compatibility with arylboronic acid with electron-withdrawing and electron-donating groups on the benzene ring.However,when heterocyclic boric acid was used as the substrate,the corresponding target product was obtained only in moderate yield,indicating that the reaction system has certain limitations to heterocyclic boric acid.Under the optimal reaction conditions,we have prepared 35 functionalized selenoether compounds.The yield of most of the target products is between 80-97%,including 2 alkyl substituted products,which proves that the system has good The suitability of the substrate.Subsequently,we tried the reaction of boric acid derivatives with diphenyl diselenide,where potassium phenyl trifluoroborate and sodium trihydroxyphenyl borate were used as raw materials to obtain the target product in 90%and 91%yields,However,when pinacol phenylboronate was used as a raw material,only a trace amount of target product was detected.Finally,we conducted a reaction scale-up experiment to expand the reaction to the gram scale,and found that the reaction can obtain the target product in good yield,and the reaction conversion rate has not decreased.The second part:On the established oxidation reaction system,the reaction of synthesizing tellurium ether with equivalent TCCA as oxidant is expanded.Using boric acid and ditellurium ether as raw materials,16 functionalized tellurium ether compounds were prepared,including 4 alkyl-substituted products,and the target product was obtained in moderate to good yields.Subsequently,we also conducted a reaction amplification experiment to expand the reaction to the gram scale,and found that the reaction can obtain the target product in good yield,and the reaction conversion rate has not decreased.In this thesis,a reaction system for synthesizing selenoether and tellurium ether with equivalent TCCA as oxidant is developed.The reaction system is carried out at room temperature,and has the advantages of low price of reaction raw materials,simple operation,mild reaction conditions,and good substrate applicability.The entire system does not need to add transition metals and alkalis,which provides another reference method for the synthesis of selenium/tellurium ether compounds.